We wish to thank the reviewer for the excellent rating for Core B and for the thoughtful comments related to the improvement of the section. They were thoughtful and to the point and we have tried to address them in this resubmission. The reviewer found our appreciation of the difficulties inherent in collecting such large anmounts of data at two different sites gratifying. Indeed, we have much experience in such things havng completed two Texas Education Association Contracts where we collected data from 20 sites around the state over four years. We also completed a Department of Education grant with three sites in other states. And in our Home project grant we have followed premature infants from two sites over 12 years. Since the original submission, we have changed space within the building and are currently advertising for two additional staff members. We did try to make the original core general with respect to the data analysis given that the analyses specific to each grant were included in the analysis section for the individual proposals. However, as suggested, we have added sections to the revision that given more detail about the individual projects within Core B. However, we have not reported each separate analysis of each hypothesis due to the number of hypotheses represented across all five RO1s. We have also added, at the reviewer's suggestion, a section dealing with the nature of the variancecovariance matrix for the mixed models to discuss how we will attempt to deal with the issue of changing variances and/or covariances over time. Given the interest of the reviewers in cross-cohort comparisons, we have added such comparisons to projects 3 and 4 in addition to project 5. Therefore, we have added a section to the Core discussing these comparisons. Our power analysis was based on our experiences with the projects listed above. We have analyzed several data sets with multilevel data and have estimated intraclass correlation between .08 and .15 over these individual studies. Based on these numbers we routinely use and ICC of .12 in power estimations for similar designs with children nested within preschool classrooms. Some of this work is in preparation for publications but none is out yet to be referenced. One addition to Core B that was not initially raised by the reviewer of Core B but by the reviewers for the other projects has to do with the language of assessment. We have made revisions to how children from homes where Spanish is spoken will be tested. These changes have meant adding a section to Core B about how these data will be analyzed. This topic will also be addressed in the individual RO1s.